XIAO Zhi-yong, WANG Gang, LIU Jie, et al. Improved apparent permeability model based on equivalent fractures
and variable slip effects analysis[J]. 2025, 46(5).
DOI:
XIAO Zhi-yong, WANG Gang, LIU Jie, et al. Improved apparent permeability model based on equivalent fractures
and variable slip effects analysis[J]. 2025, 46(5).DOI: 10.16285/j.rsm.2024.1008.
Improved apparent permeability model based on equivalent fractures
and variable slip effects analysis
滑脱效应可以显著增强裂隙性岩石的渗透率,正确认识滑脱效应的影响对了解储层内气体流动规律具有重要意义。现有理论模型大多认为本征渗透率和滑脱系数均为常数,且对滑脱效应显著的临界孔隙压力没有较好的界定方式。为此,基于等效裂隙和岩桥模型,建立了一个动态表观渗透率模型,该模型认为滑脱系数和本征渗透率是与有效应力和吸附膨胀有关的函数。在建立的动态表观渗透率模型基础上,分析了不同围压和不同渗透介质下本征渗透率和滑脱系数的动态变化,提出了滑脱效应贡献率计算了滑脱效应显著的临界孔隙压力。研究结果表明:(1)本征渗透率随孔隙压力增加而增加,滑脱系数则相反;(2)对于不同渗透介质,本征渗透率随孔隙压力的增加趋势与气体吸附性能有关,滑脱系数的变化则更加复杂;(3)滑脱效应贡献率与孔隙压力之间呈幂函数关系,滑脱效应显著的临界孔隙压力N2<CO2<He。本研究可以为裂隙性岩石的渗透率预测和现场开采提供一定的理论指导。Theslip effect can significantly enhance the permeability of fractured rock
andunderstanding its influence is crucial for comprehending gas flow dynamicswithin reservoirs. Most existing theoretical models treat intrinsicpermeability and slip coefficient as constants and lack a method to define thecritical pore pressure where the slip effect becomes significant. Thus
adynamic apparent permeability model was developed based on equivalent fractureand rock bridge models
considering slip coefficient and intrinsic permeabilityas functions of effective stress and adsorption swelling. Using the establisheddynamic apparent permeability model
we analyzed variations in intrinsicpermeability and slip coefficient under different confining stresses andpermeable media. Additionally
we introduced the concept of the slipeffect contribution rate to identify the critical pore pressure where the slipeffect becomes significant. The results indicate that: 1) Intrinsicpermeability increases with rising pore pressure
while slip coefficientsdecrease; 2) For different permeablemedia
the increase in intrinsic permeability with pore pressure is linked togas adsorption properties
and slip coefficient variation is more complex; 3) Apower function relationship exists between the slip effect contribution rateand pore pressure
with the critical pore pressure order being N2<CO2<He.This study offers theoretical guidance for predicting permeability andextracting resources from fractured rocks.
Abstract
The slip effect can significantly enhance the permeability of fractured rock
and understanding its influence is crucial for comprehending gas flow dynamics within reservoirs. Most existing theoretical models treat intrinsic permeability and slip coefficient as constants and lack a method to define the critical pore pressure where the slip effect becomes significant. Thus
a dynamic apparent permeability model was developed based on equivalent fracture and rock bridge models
considering slip coefficient and intrinsic permeability as functions of effective stress and adsorption swelling. Using the established dynamic apparent permeability model
we analyzed variations in intrinsic permeability and slip coefficient under different confining stresses and permeable media. Additionally
we introduced the concept of the slip effect contribution rate to identify the critical pore pressure where the slip effect becomes significant. The results indicate that: 1) Intrinsic permeability increases with rising pore pressure
while slip coefficients decrease; 2) For different permeable media
the increase in intrinsic permeability with pore pressure is linked to gas adsorption properties
and slip coefficient variation is more complex; 3) A power function relationship exists between the slip effect contribution rate and pore pressure
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TIAN Kun-yun
ZHANG Rui-lin
ZHANG Hong-xue
LIU Wei-qun
LIU Wei
LI Yin-ping
ANG Chun-he
MA Hong-ling
Related Institution
School of Resources and Safty Engineering, China University of Mining and Technology(Beijing)
School of Safty Science&Engineering, Henan Institute of Engineering
State Key Laboratory for Geomechanics & Deep Underground Engineering, China University of Mining and Technology
College of Sciences, Anhui University of Science & Technology
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences